Enhanced anti-bacterial properties and thermal regulation via photothermal conversion with localized surface plasmon resonance effect in cotton fabrics

Enhanced anti-bacterial properties and thermal regulation are realized in cotton fabrics cross-linked with hybrid poly(di(ethylene glycol) methyl ether methacrylate-co-oligo(ethylene glycol) methyl ether methacrylate-co-ethylene glycol methacrylate) nanogels containing gold nanoparticles (Au NPs), denoted as hybrid P(MA-co-MA₃₀₀-co-EGMA)/Au nanogels. Pure P(MA-co-MA₃₀₀-co-EGMA) nanogels are synthesized by emulsion polymerization as carriers and then embedded with Au NPs via in-situ reduction. By applying 1,2,3,4-butanetetracarboxylic acid as a cross-linker and changing the amount of hybrid P(MA-co-MA₃₀₀-co-EGMA)/Au nanogels in solution, the weight gain ratios of hybrid nanogels on cotton fabrics are set as 10 % (CHN-10) and 20 % (CHN-20). Due to the densely packed structure of the hybrid nanogels on the surface, the localized surface plasmon resonance (LSPR) effect of the Au NPs improves the photothermal conversion capability and converts the absorbed light energy into thermal energy. Simply illuminating with visible light, the surface temperature of CHN-20 pronouncedly increases from 20.4 to 43.0 °C in 50 s. The increased local temperature induces the denaturation of protein and the death of bacteria on the surface. Thus, an illumination with visible light for 2 h results in an anti-bacterial rate for S. aureus of 100 % for CHN-20. Additionally, it presents an excellent thermal regulation capability via photothermal conversion and can be used for continuously maintaining human body temperature in cold areas. Because no additional chemical agents and external power source are required for the anti-bacterial properties and thermal regulation, the obtained cotton fabrics cross-linked with hybrid P(MA-co-MA₃₀₀-co-EGMA)/Au nanogels are eco-friendly and suitable for smart textiles in daily wear.